An Atomtronic Study of Two-Dimensional Transport in Disordered Waveguides

Abstract

This thesis builds upon the concept of quantum simulation, where an inherently quantum system functions as an analogue computer. The programming of the dynamics in the simulator is done through the controlled engineering of the Hamiltonian that describes the time evolution of an ensemble of ultracold atoms. This enables multiple systems of interest to be studied in a controllable environment, providing an alternative to the sought after `quantum computer'. The quantum simulator developed at the University of Auckland is presented, highlighting the elements used to provide the necessary degree of control over the system dynamics. Furthermore, we present a series of transmissive experiments conducted on a twodimensional degenerate quantum gas of 87Rb designed to study quantum transport eects. Starting from a Bose-Einstein condensate, the atoms are loaded into a twodimensional trap with a superimposed customizable optical potential. created by imaging a spatial light modulator. We focus on a potential consisting of two reservoirs and a connecting channel that functions as an atomic waveguide. An `atomtronic' approach to the study of transport properties in the potential allows us to model the dynamics as an analogous electronic system. Addition of point-like disorder in the potential enables the study of Anderson localization eects through the measurement of an eective channel resistance. The observed dynamics of the atomic conductance in long channels is consistent with quantum interference eects, showing signatures of two-dimensional Anderson localization.